Systems for measuring properties such as concentration or turbidity of a wide range of samples such as dispersions, gas mixtures, solutions, suspensions, colloids, aerosols, foams, emulsions, gels, and/or sols, are useful in many fields. For example, environmental quality standards can be based on turbidity or a concentration of suspended particulates in a sample, as measured by a nephelometer or other turbidimeter. Accurate measurements of the concentration of samples in food, pharmaceutical, and biotechnology industries can allow improvement in yields and quality control and assurance in production processes. Conventional methods tend to be overly complex and often require careful calibration and signal analysis. Improved methods for making these and other measurements are desirable.